The P0891 trouble code indicates a high signal from the Transmission Control Module (TCM) power relay sense circuit.
P0891 TCM Power Relay Sense Circuit High
Code symptoms P0891.
1. Check Engine Light (CEL) illuminated on the dashboard.
2. Possible transmission shifting issues.
3. Vehicle may enter “limp mode,” limiting performance.
4. Other related trouble codes may be present.
Causes of the code P0891.
1. Faulty Transmission Control Module (TCM) power relay.
2. Wiring or connector issues in the power relay sense circuit.
3. Poor electrical connection or corrosion in the relay or circuit connector.
4. Problems with the transmission control module (TCM).
5. Internal transmission issues affecting power relay function.
Code Solutions P0891.
1. Inspect and replace the Transmission Control Module (TCM) power relay if it’s faulty.
2. Check and repair any damaged wiring or connectors in the power relay sense circuit.
3. Ensure good electrical connections and clean any corrosion from connectors.
4. If the issue persists, further diagnostics may be necessary to identify internal transmission problems.
5. Clear the trouble codes from the vehicle’s computer after repairs are complete.
6. Test drive the vehicle to confirm that the issue has been resolved.